Liquid level gages are used to determine the level of liquid in vessels (such as boilers, tanks, and drums). Viewing may occur directly or remotely (for example, using a camera). A prior art liquid level gage is described and shown in U.S. Pat. No. 3,187,573 (the “Goellner Patent”), which is incorporated herein by reference. This liquid level gage is commercially available under the SIMPLIPORT water level gage product line from Clark-Reliance Corporation. In operation, a user views the ports of the liquid level gage to determine the level of liquid in the vessel. Ports below the level of liquid in the vessel are displayed as green, and ports above the level of liquid in the vessel are displayed as red.
Prior liquid level gages are typically illuminated by flood lights and color filters. Liquid level gages that are illuminated by flood lights are undesirable because flood lights require a high voltage power supply, radiate large amount of heats, do not provide precise illumination, and require a great deal of maintenance. Therefore, a need exists for a liquid level gage that overcomes the deficiencies in the existing liquid level gages.